1. Field of the Invention
This invention relates to improved packaging for integrated circuit structures. More particularly, this invention relates to an improved lead assembly for an integrated circuit structure to reduce crosstalk and coupling and provide additional improvements.
2. Description of the Related Art
In the conventional packaging of integrated circuit structures with traditional leadframe patterns, the die may be attached to the center paddle of a metal lead frame which has a plurality of metal leads which fan out from a series of bonding pads arranged around the four sides of the die. The respective widths of these leads may vary along their lengths from their inner ends, adjacent the die, to the outer ends of the leads. The respective lengths of these leads will also show a large difference.
In addition, the generally parallel spacing and long coupling lengths between the leads, which extends all the way to the outside perimeter of the package, can result in coupling of the signals on adjacent leads. Varying widths among these leads means that characteristic impedance levels are not controlled and matched which can result in signal reflection. The varying of the lead lengths may result in differences in signal propagation delay.
In Hayward et al U.S. Pat. No. 4,801,999, which is assigned to the assignee of this invention, there is shown a lead assembly in which leads and busses are arranged on both sides of a dielectric layer. However, the leads are still arranged around the die in generally parallel configuration to adjacent leads.
It would, therefore, be desirable to provide an integrated circuit lead assembly structure wherein coupling and crosstalk between adjacent signal lines can be controlled, signal reflection can be minimized, and signal propagation delay can be equalized.